This section is intended to introduce various aspects of the art, which may be associated with exemplary embodiments of the present disclosure. This discussion is believed to assist in providing a framework to facilitate a better understanding of particular aspects of the present disclosure. Accordingly, it should be understood that this section should be read in this light, and not necessarily as admissions of prior art.
Field of the Invention
The present disclosure relates to the field of well completions. More specifically, the present invention relates to the isolation of formations in connection with wellbores that have been completed through multiple zones. The application also relates to a wellbore completion apparatus which incorporates bypass technology that allows for in-flow control of production fluids through primary and secondary flow paths along the wellbore.
Discussion of Technology
In the drilling of oil and gas wells, a wellbore is formed using a drill bit that is urged downwardly at a lower end of a drill string. After drilling to a predetermined depth, the drill string and bit are removed and the wellbore is lined with a string of casing. An annular area is thus formed between the string of casing and the formation. A cementing operation is typically conducted in order to fill or “squeeze” the annular area with cement. The combination of cement and casing strengthens the wellbore and facilitates the isolation of formations behind the casing.
It is common to place several strings of casing having progressively smaller outer diameters into the wellbore. The process of drilling and then cementing progressively smaller strings of casing is repeated several times until the well has reached total depth. The final string of casing, referred to as a production casing, is cemented in place and perforated. In some instances, the final string of casing is a liner, that is, a string of casing that is not tied back to the surface.
As part of the completion process, a wellhead is installed at the surface. The wellhead controls the flow of production fluids to the surface, or the injection of fluids into the wellbore. Fluid gathering and processing equipment such as pipes, valves and separators are also provided. Production operations may then commence.
It is sometimes desirable to leave the bottom portion of a wellbore open. In open-hole completions, a production casing is not extended through the producing zones and perforated; rather, the producing zones are left uncased, or “open.” A production string or “tubing” is then positioned inside the open wellbore extending down below the last string of casing.
There are certain advantages to open-hole completions versus cased-hole completions. First, because open-hole completions have no perforation tunnels, formation fluids can converge on the wellbore radially 360 degrees. This has the benefit of eliminating the additional pressure drop associated with converging radial flow and then linear flow through particle-filled perforation tunnels. The reduced pressure drop associated with an open-hole completion virtually guarantees that it will be more productive than an unstimulated, cased hole in the same formation.
Second, open-hole techniques are oftentimes less expensive than cased hole completions. For example, the use of slotted base pipes eliminates the need for cementing, perforating, and post-perforation clean-up operations. Alternatively, the use of a sand screen, with or without a gravel packs along the open hole wellbore, helps maintain the integrity of the wellbore while allowing substantially 360 degree radial formation exposure.
It is desirable in some open-hole completions to isolate selected zones along the wellbore. For example, it is sometimes desirable to isolate an interval from the production of formation fluids into the wellbore. Annular zonal isolation may also be desired for production allocation, production/injection fluid profile control, selective stimulation, or gas control. This may be done through the use of packers (or a zonal isolation apparatus) that has bypass technology. The bypass technology may employ packing conduits that permit fluids to flow through a sealing element of the packer and across an isolated zone.
The use of bypass technology with a zonal isolation apparatus has been developed in the context of gravel packing. This technology is practiced under the name Alternate Path®, owned by ExxonMobil Corporation of Irving, Tex. Alternate Path® technology employs shunt tubes, or alternate flow channels, that allow a gravel slurry to bypass selected areas, e.g., premature sand bridges or packers, along a wellbore. Such fluid bypass technology is described, for example, in U.S. Pat. No. 5,588,487 entitled “Tool for Blocking Axial Flow in Gravel-Packed Well Annulus,” and PCT Publication No. WO2008/060479 entitled “Wellbore Method and Apparatus for Completion, Production, and Injection,” each of which is incorporated herein by reference in its entirety. Additional references which discuss alternate flow channel technology include U.S. Pat. No. 8,215,406; U.S. Pat. No. 8,186,429; U.S. Pat. No. 8,127,831; U.S. Pat. No. 8,011,437; U.S. Pat. No. 7,971,642; U.S. Pat. No. 7,938,184; U.S. Pat. No. 7,661,476; U.S. Pat. No. 5,113,315; U.S. Pat. No. 4,945,991; U.S. Pat. Publ. No. 2012/0217010; U.S. Pat. Publ. No. 2009/0294128; M. T. Hecker, et al., “Extending Openhole Gravel-Packing Capability: Initial Field Installation of Internal Shunt Alternate Path Technology,” SPE Annual Technical Conference and Exhibition, SPE Paper No. 135,102 (September 2010); and M. D. Barry, et al., “Open-hole Gravel Packing with Zonal Isolation,” SPE Paper No. 110,460 (November 2007). The Alternate Path® technology enables a true zonal isolation in multi-zone, openhole gravel pack completions.
In some open-hole completions, a gravel pack is not employed. This may be due to the formation being sufficiently consolidated that a sand screen and pack are not required. Alternatively, this may be due to economic limitations. In either instance, it is still desirable to run tubular bodies down the wellbore to support packers or other tools, and to provide flow control between a main base pipe and the annulus formed between the base pipe and the surrounding wellbore.
In this instance, a need remains for an improved sand control assembly that provides flow control between a base pipe and a surrounding annular region using fluid bypass technology while filtering production fluids. A need further exists for a sand screen assembly that provides multi-tier subsurface flow control, enabling fluid communication between a primary flow path within the base pipes and alternate flow paths of fluid transport conduits. Additionally, a need exists for a method of completing a wellbore wherein a sand screen assembly is placed along a formation that uses selected fluid communication between the base pipe and bypass channels.